Recent advances in the utilization of polyaniline in protein detection: a short review

Abstract

Various reports have been published based on covalently attaching biomolecules to polyaniline (PANI). The functional groups connected to the surface of polymeric units determine the immobilization method as well as the method of detection. The present mini-review aims at covering recent advances in the field of protein binding and detection using PANI. Several proteins have been attached to the polymer using different immobilization techniques. The application of PANI in protein detection has also been discussed along with the future scope of these materials in diagnosis and detection.

Fig. 1. Different redox states of PANI.

Fig. 2. (A) SEM image of non-functionalized single PANI nanowire. (B) SEM image of functionalized single PANI nanowire with IgG mAbs. (C) Measurement of conductance changes on single non-functionalized PANI nanowire (a: PBS; b: BSA, 10 μg mL⁻¹; and c: IgG, 3.3 μg mL⁻¹). (D) Specificity test of functionalized single PANI nanowire with IgG mAbs (a: PBS; b: BSA, 50 ng mL⁻¹; and c: IgG, 33 ng mL⁻¹) (reprinted with permission from Elsevier, ref. Lee et al., (2011)).

Fig. 3. (a) Schematic illustration of the synthesis of MIP-PANI particles and the fabrication of MIP-PANI sensor, (b) EIS curves and (c) CV curves of MIP-PANI particles modified electrode in [Fe(CN)6]^3−/4− solution before extraction, after extraction and after rebinding OVA by incubation in 0.5 mg mL⁻¹ OVA solution (reprinted with permission from Elsevier, ref. Luo et al., (2017)).

Fig. 4. Functionalization of PANI coated filter paper. The amine groups of PAni bonds with the one of the two aldehyde (–CHO) groups of Glut. The other –CHO group is available for covalent bonding with the amine groups of the antibodies. A wash step is present between each modification step (reprinted with permission from IEEE, ref. Mondal et al., (2017)).

Fig. 5. Schematic of the systematic protocol for SPCE surface modification and immunosensing. PANI – polyaniline; AuNCs – gold nanocrystals; HSA – human serum albumin; Ab-HSA – anti-human, serum albumin antibody; BSA – bovine serum albumin; EIS – electrochemical impedance spectroscopy (reprinted with permission from MDPI, ref. Shaikh et al., (2019)).

Fig. 6. An illustration and the experimental set-up of the single polyaniline (PANI) nanowire biosensor to detect cardiac biomarkers. (a) The experimental setup; the microfluidic channel is adhered on the nanowire biosensor and the nanowire biosensor chip is mounted on a probe station connected to the semiconductor analyzer and syringe pump with inlet and outlet; (b) the conductance change in the single PANI nanowire-based biosensor is monitored. The injection of PBS (mark a), BSA (mark b), and cardiac biomarker (mark c) shows the different changes of conductance (reprinted with permission from MDPI, ref. Lee et al., (2017)).

Fig. 7. (a) AFM topography of the electrodeposited PANi film on Si surface; line (left image) and region (right image) analysis to estimate the average height of the deposited film. Data suggest the formation of thin film of 45–50 nm with globular PANi structures, (b) current–voltage characteristic (regression data) of the PAni–Si substrate and the formed biosensor ‘anti-human IgG–PAni–Si’. Ohmic conduction characteristics are evident with average conductivities of 45 μS for the PAni–Si substrate and 32 μS for the formed bioelectrode (reprinted with permission from Elsevier, ref. Deep et al., (2012)).

Fig. 8. Schematic illustration of the fabrication process of the electrochemical IgG biosensor based on a BSA/PANI-NW antifouling interface (reprinted with permission from American Chemical Society, ref. Li et al., (2021)).

Fig. 9. Schematic representation of construction and development of the immunosensor (reprinted with permission from Avicenna Journal of Medical Biotechnology, ref. Dutta et al., (2020)).

Fig. 10. Stepwise fabrication process of the immunosensor. (a) The bare GCE, (b) PANI nanowires electrodeposited on the GCE, (c) the formation of HA/PANI composite wires, (d) CEA antibody immobilization, (e) specific CEA capturing and the antifouling towards nonspecific protein and (f) DPV current signal recording (reprinted with permission from Springer, ref. Wang et al., (2018)).

Fig. 11. Schematic of the N-MIP sensor (reprinted with permission from Elsevier, ref. Karimi et al., (2019)).

Ufana Riaz

Nuzhat Nabi

India Pointer

Amit Kumar

Darlene. K. Taylor